Section Acarphaea is distinctive by its farinose indument and base chromosome number of 8, among other traits; it could prove to be a separate, convergent genus. Natural and artificial hybrids have been documented among some members of sect. Chaenactis (see further dis-cussion there). Reports of hybrids among species of the other two sections are few and doubtful. Chaenactis appears to be most closely related to the monotypic Dimeresia and Orochaenactis, which B. G. Baldwin et al. (2002) treated together as a narrowly circumscribed tribe, Chaenactideae.